As semiconductor devices have been miniaturized and 3D devices have been widely used, regions such as deep hole patterns where a signal is less likely to be detected have increased. On the other hand, there is a growing need to observe the regions. Therefore, a scanning electron microscope (SEM) used in inspecting and measuring semiconductors requires higher sensitivity and higher accuracy than those in the related art.
The contrast of a deep hole bottom can be emphasized by selectively detecting an electron discharged in a specific direction from electrons discharged from a sample. An electron microscope disclosed in PTL 1 can selectively detect the electron discharged in the specific direction by arranging a plurality of detectors at a target position where an electron beam optical axis serves as a symmetrical axis. In addition, in order to reduce a rotation effect of a signal electron which is caused by an objective lens magnetic field in discriminating the signal electron generated in a detector azimuth, an acceleration electrode is installed in a magnetic field generation region. The signal electron is caused to pass through the region in a state where the signal electron holds high energy. In this manner, azimuth information is stored. PTL 2 discloses an electron microscope in which four detectors are arranged so as to have a relative angle of 90° at a symmetrical position where the electron beam optical axis serves as the symmetrical axis. Since the plurality of detectors are arranged in this way, it is possible to selectively detect the electron discharged in the specific direction. PTL 2 discloses a method in which a sum or a difference between a signal based on the electron discharged in a direction capable of improving the contrast of a lower layer pattern and a signal based on the electron discharged in other directions is output as an image signal.